Used to idle at 13, now it wants 10 AFRs???

[rvannly]

Did you run the bpr8's when it was idling at 13 afr? or did you recently go colder?

 

I've installed over 4 Lc-1's on differents cars and after a few months they all either went bad or put out incorrect readings. I called them and the person on the other side told me they were getting more and more calls about the same problem. I noticed there was some changes in the Lc-1 gauge; I, personally had the gauge with a flat face and never had problems. They now sell gauges with a round face, as in convexed plastic front cover, and those were the ones that I've had problems with.

 

I now tune with the first gen LM-1

Edited October 24, 2009 by rvannly
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[cygnusx1]

Is it possible that the wasted spark is igniting left over gasses in the chamber during the valve overlap cycle? That would explain the puff I hear in the exhaust when the "misfire" happens.

 

The problem started with the second re-install of the fuel tank, and the old set of plugs that always ran fine. The problem continued with the new plugs, of a colder range. (I changed to see if this new problem would go away) I think I went from NGK 7's to 8's and saw no change in the issue.

 

As far as the LC1 goes, it still reads the same AFR's as it did when it was new with the corresponding archived maps I tried reloading. So I can say that it is reading as consistently as it was when I installed it. I can also confirm that it is idling rich at 10:1 because of the smoke/smell I get when it idles for a while.

 

I have boiled this down to a few things:

1)Fuel Delivery issue at idle (air bubbles in the lines?)

2)Funky injector(s) (dribbling or bad atomization?)

3)Compression loss at idle (leaky head gasket or crack somewhere?)

4)Ignition miss (which I cannot duplicate with a test light or visual spark observation.)

5)Wasted spark is igniting exhaust gasses (longshot?)

[blueshark123]

Dave have you checked your fuel filter and done a compression or leak down test yet?

[niner11]

Dave, I'm certainly not out of ideas yet but I was wondering if you could take a close look at an old data log that you might have using the same Msq file for megasquirt that used to work fine for you. Maybe try to compare that to a brand new data log and then start to look for differences specific to duty cycles and pulswidth. It would take very little effort and who knows maybe something will show up.

 

I do like the compression check idea because its so easy and allows you to move on to other things.

[cygnusx1]

OK I solved the problem but I still can't explain why it happened.

 

I was determined to look for the simple things so I decided to re-chack the gap on the new plugs I had installed while trying to slove this problem. The misfires were at idle and slightly at part throttle with the old spark plugs and also the new colder plugs.

 

When I pulled out the latest plugs tonight, they looked pretty nice. But I noticed that the ground electrode completely covered the core. I had been reading about side-gapping plugs in Grumpy's thread, so I decided to try it.

 

I bent the ground tab up about 45 degrees, ground it about half way down on the bench grinder. Cleaned up the end with a small file and re-gapped them. Now the spark is going to have nice exposure to the combustion chamber. I installed them, crossed my fingers and fired up the car. Wow. Smooth idle, no missing but, as the car warmed up, the idled settled a bit low. I drove it, SUPER smooth power, and I came back and leaned out to idle mix from 10:1 to about 12.3:1 and it idles nice and smoothly.

 

Hmm.

 

This is NO B.S. Side gapping works!

http://performanceunlimited.com/documents/plugsidegapping.html

 

My Alfa Romeo used to use Golden Lodge spark plugs that had four side gaps! This was factory spec for Alfa in 1972!

[niner11]

This makes me want to index my plugs tomorrow!

[ZR8ED]

This reminds me of my weber tuning days. Don't blame anything until you check condition/gap of plugs. Once fouled. Ditch em! Keep using fresh clean gapped plugs until tuning is done.

 

I am having trouble picturing what you did to the plugs. Do you have pics or link?

 

Makes me want to check my plugs too. (not that the car is running poorly) Just a good reminder.

 

Soooo does this mean that your compression IS ok? Did you check it?hehe

 

Glad you sorted it out.

[cygnusx1]

Never checked compression LOL. Call me stubborn. The car pushed you back in the seat pretty hard so I doubted it was compression anyhow. If I had a tester handy, it would have been the first thing I checked. I just hate to buy tools I only will need once or twice while I am on a pretty tight budget.

 

The plugs were brand new NGK BPR8..'s. This mod, changes the way the car burns fuel. It even smells cleaner now and my AFR's are more stable. In theory, with the spark leaned over about 45 degrees, the flame front heads for the piston rather than the cylinder walls.

 

http://performanceunlimited.com/documents/plugsidegapping.html

 

 

 

 

 

[CamH]

I've been thinking about giving this a shot because my AFR's are never very stable. I started trying it on some old plugs and found it to be very difficult to do! How many spark plugs did it take you to get it right? Did you accidentally cut any at an angle? How precise do you think this needs to be?

[softopz]

hey zr8ted you poking fun lol Iam just throwing ideas based on what dave was giving us. I also suggested... and i quote from my post #20

 

-Did you put your old plugs back and see what happened? you had said that was some of your recent changes. that would be the first thing I would do.

 

aha that was one suggestion and others that were plausible.

 

anyways back to discussion Iam going try this on my l28et EDIS I do have some misses here and there.

[niner11]

After reading this I side gapped my plugs and indexed them. Can't comment on any power increases but the car idles very smooth. I'm also running an MSD 6al

[cygnusx1]

It definitely smooths out the idle and cleans up the exhaust a little. No doubt. BTW my old plugs were misfiring, which is why I put in the new ones. There were no improvements until I side gapped the new ones.

 

This probably has a nice positive effect on our cars combustion process, especially at low flow conditions, due to the antiquated combustion chamber design. Besides it doesn't take a genius to see that the spark is totally covered by the metal bar on a stock plug. Isn't that kind of strange?

 

One of the big automakers is experimenting with laser ignition. They focus laser beams on a spot in mid-air, dead center in the combustion chamber, so that the explosion is symmetric about the piston head. Yes it does matter where and how the gas ignites.

 

http://www.es.anl.gov/Energy_systems/distributed_energy/documents/laser%20ignition_single%20cylinder%20studies_011006.pdf

[softopz]

thats interesting, I am going to try that side index while I am doing my port to the intake. My thoughts are exactly like yours dave its all about better firing especially atomization of the fuel. Not to long ago I did a mild port job to the head... especially after reading BRaap thread for head modifcation I concentrated allot on the upper area where the fuel is being sprayed by injector. My concern is when I install the supra injectors they dont protrude as much in the manifold like the zxt injector this will cause dripping into manifold and poor ignition of mixture/poor idle.

Ill be seeing the difference it will do with that area ported to match like the head is. More in my post here http://forums.hybridz.org/showthread.php?t=156370 tomorrow ill mount all the stock injector in a clear platic box and take video of spray pattern then do the same for the supra injectors. Then re do the test with the injector body ported .